Ensure that errors have stack traces attached.

pkg/barback/lib/src/serialize.dart

Index: pkg/barback/lib/src/serialize.dart
diff --git a/pkg/barback/lib/src/serialize.dart b/pkg/barback/lib/src/serialize.dart
index eb948a451fe7ad68c1a5d551fa1138f16998dd59..fa5adeaba5d2f1fb069004e376ad1aabcf2ca314 100644
--- a/pkg/barback/lib/src/serialize.dart
+++ b/pkg/barback/lib/src/serialize.dart
@@ -61,7 +61,8 @@ StreamSubscription _deserializeTransformer(Stream input, bool cancelOnError) {
     if (data['type'] == 'data') {
       sink.add(data['data']);
     } else if (data['type'] == 'error') {
-      sink.addError(new CrossIsolateException.deserialize(data['error']));
+      var exception = new CrossIsolateException.deserialize(data['error']);
+      sink.addError(exception, exception.stackTrace);
     } else {
       assert(data['type'] == 'done');
       sink.close();